title: Caffeine challenge and breath-holding duration in patients with panic disorder.
abstract: OBJECTIVE
  Breath-holding (BH) has been used as a simple probe to increase endogenous carbon dioxide (CO2). In patients with Panic Disorder (PD), lower baseline BH duration is associated with caffeine-induced panic attacks. In this paper, we assessed BH duration in PD patients in relation to panic attacks induced by caffeine intake.
  
  
  METHODS
  BH duration and state anxiety were assessed in 40 PD patients (12 males), both at baseline and after a 400-mg caffeine challenge test.
  
  
  RESULTS
  Patients panicking after caffeine administration (14 patients, 4 males) exhibited a significant reduction of their post-challenge BH duration, while no change of the BH duration was observed in non-panicking patients (26 patients, 8 males). Reduction in post-challenge BH duration was not related to higher anxiety levels--as reflected in the State-Trait Anxiety Inventory-State Form scores--independently of the occurrence of a panic attack. Panickers exhibited significantly lower baseline BH duration, compared to non-panickers.
  
  
  CONCLUSIONS
  Our findings indicate that in PD patients, caffeine-induced panic attacks are strongly associated with a significant reduction of BH duration at both pre- and post-challenge. Jointly, these findings suggest that in a subgroup of PD patients, sensitivity to endogenous CO2 accumulation may underlie both the lower BH durations and the caffeine-induced panic attacks. In this subgroup of PD patients, caffeine might exert its panicogenic properties through the exacerbation of patients' already pathological hypersensitivity to CO2 accumulation, as indicated by both the significant decrease of their BH duration at post-challenge and by their significantly lower baseline BH duration respectively.
authors.affiliation: Athens University Medical School, 1st Department of Psychiatry, Eginition Hospital, 74 Vas. Sofias Avenue, 11528 Athens, Greece. vmasdrakis@med.uoa.gr
authors.forename: Vasilios G
authors.initials: VG
authors.lastname: Masdrakis
authors.forename: Manolis
authors.initials: M
authors.lastname: Markianos
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Vaidakis
authors.forename: Yiannis G
authors.initials: YG
authors.lastname: Papakostas
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Oulis
mesh_terms: D000328:Adult; D001237:Asphyxia / Q000378:metabolism; D002110:Caffeine / Q000009:adverse effects*; D002245:Carbon Dioxide / Q000378:metabolism; D005260:Female; D006801:Humans; D008297:Male; D016584:Panic Disorder / Q000139:chemically induced / Q000209:etiology / Q000503:physiopathology*; D012119:Respiration
chemical_list: D002245:Carbon Dioxide; D002110:Caffeine